7. design rules


(a) Distinguish between principles, guidelines and standards, using examples of each to illustrate.

(b) Why is context important in selecting and applying guidelines and principles for interface design? Illustrate your answer with examples.

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(a) Principles are abstract design rules which can be said to generally apply to all systems, e.g. an interface should be predictable. Guidelines are rules that are more concrete but also generally applicable, e.g. group related functional items together. Principles and guidelines are recommendations - they do not have authority. Standards are rules laid down by official bodies (such as ISO), which must be complied with; i.e. they have authority and they are more specific than the other two. Standards may outline specific orders - of display of options, for example.

(b) Both are context dependent to a degree, although principles are more universally applicable than guidelines. However, even principles are context dependent, e.g. predictability is a principle that might not apply to a computer game. Guidelines are based on psychological theory and it is important that 1. the theory is sound and that 2. the context in which the rule is applied is comparable to that of the theory. If not, the guideline may not be relevant to the particular situation. Standards encapsulate all of this.

Other exercises in this chapter

ex.7.1 (ans), ex.7.2 (ans), ex.7.3 (open), ex.7.4 (ans), ex.7.5 (ans), ex.7.6 (ans), ex.7.7 (tut), ex.7.8 (tut), ex.7.9 (open), ex.7.10 (tut), ex.7.11 (tut), ex.7.12 (tut), ex.7.13 (tut)

all exercises for this chapter